how gr operators work?

I tried to run example given there but it is not working,

where can I get more examples to understand working of Gr operators work?

specially for raychaudhuri equations.

I see two recent items on the web about Mathematica and the rosettacode.org site. One was a Wolfram Inc. corporate blog post, and the other a post on Wolfram's relatively new community site.

There are many items on the page of tasks still without a submitted Maple implementation. It would be nice to see interesting implementations of some remaining tasks, as contributions from the Maple user base. The tasks remaining are of very mixed difficulty levels.

To date there are only 132 entries on the page for Maple implementations of that site's programming tasks. (Of these about 40 were submitted by one member while about 80 were submitted by another member.)

acer

Hi MaplePrime-ers,

I'm using Maple17 in Matlab 2012b to evaluate a symbolic function over a grid of values.  The number of values is generally ~500k, and therefore I have a loop that dumps the solutions into MATLAB where the values are parsed and stored more efficiently.

I put this proceess in an optimization routine, and I keep getting crashes.  The crashes are NOT repeatable.  They generally happen after 4-10 times the routine has been called.  

This is one of the stack dumps.  Anybody have any ideas?  I talked to MATLAB support, but they weren't very useful (they started pointing fingers).

------------------------------------------------------------------------
Segmentation violation detected at Wed Jun 4 17:38:11 2014
------------------------------------------------------------------------

Configuration:
Crash Decoding : Disabled
Current Visual : 0x24 (class 4, depth 24)
Default Encoding: UTF-8
GNU C Library : 2.15 stable
MATLAB Root : /opt/Matlab/R2012b
MATLAB Version : 8.0.0.783 (R2012b)
Operating System: Linux 3.2.0-37-generic #58-Ubuntu SMP Thu Jan 24 15:28:10 UTC 2013 x86_64
Processor ID : x86 Family 6 Model 23 Stepping 6, GenuineIntel
Virtual Machine : Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot(TM) 64-Bit Server VM mixed mode
Window System : The XFree86 Project, Inc (40300000), display wildnode0:15.0

Fault Count: 1

Abnormal termination:
Segmentation violation

Register State (from fault):
RAX = 00007f3bcc0a80c0 RBX = 00007f3b97fe6000
RCX = 0000000000000000 RDX = 00007f3bcc0a84a0
RSP = 00007f3b8cb29d60 RBP = 0000000000000003
RSI = 5851f42d4c957f2d RDI = 00007f3bde026360

R8 = 65a1566174cc9e28 R9 = 0000000000000002
R10 = 00007f3b8cb29d90 R11 = 0000000000002e88
R12 = 0000000000000001 R13 = 00007f3b8cb29df0
R14 = 0000000000000000 R15 = 0000000000000003

RIP = 00007f3b977d0604 EFL = 0000000000010283

CS = 0033 FS = 0000 GS = 0000

Stack Trace (from fault):
[ 0] 0x00007f3c962b01de /opt/Matlab/R2012b/bin/glnxa64/libmwfl.so+00516574 _ZN2fl4diag15stacktrace_base7captureERKNS0_14thread_contextEm+000158
[ 1] 0x00007f3c962b14b2 /opt/Matlab/R2012b/bin/glnxa64/libmwfl.so+00521394
[ 2] 0x00007f3c962b2ffe /opt/Matlab/R2012b/bin/glnxa64/libmwfl.so+00528382 _ZN2fl4diag13terminate_logEPKcRKNS0_14thread_contextE+000174
[ 3] 0x00007f3c9559f093 /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00557203 _ZN2fl4diag13terminate_logEPKcPK8ucontext+000067
[ 4] 0x00007f3c9559bb9d /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00543645
[ 5] 0x00007f3c9559d835 /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00550965
[ 6] 0x00007f3c9559da55 /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00551509
[ 7] 0x00007f3c9559e0fe /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00553214
[ 8] 0x00007f3c9559e295 /opt/Matlab/R2012b/bin/glnxa64/libmwmcr.so+00553621
[ 9] 0x00007f3c93a86cb0 /lib/x86_64-linux-gnu/libpthread.so.0+00064688
[ 10] 0x00007f3b977d0604 /opt/maple17/bin.X86_64_LINUX/libmaple.so+01824260
[ 11] 0x00007f3b977cfc48 /opt/maple17/bin.X86_64_LINUX/libmaple.so+01821768
[ 12] 0x00007f3b977d2f88 /opt/maple17/bin.X86_64_LINUX/libmaple.so+01834888
[ 13] 0x00007f3b9763d63f /opt/maple17/bin.X86_64_LINUX/libmaple.so+00173631
[ 14] 0x00007f3c93a7ee9a /lib/x86_64-linux-gnu/libpthread.so.0+00032410
[ 15] 0x00007f3c937ab3fd /lib/x86_64-linux-gnu/libc.so.6+01000445 clone+000109

If this problem is reproducible, please submit a Service Request via:
http://www.mathworks.com/support/contact_us/

A technical support engineer might contact you with further information.

Thank you for your help.

> restart;
> with(LinearAlgebra);
> q := a*mu^4+b*mu^3+d*mu^2+e*mu+f = 0;
> sol := solve(a*mu^4+b*mu^3+d*mu^2+e*mu+f = 0, mu);
> S[1] := allvalues(sol);
> PARAM := [a = -54/c^2-1269*A[1]/(8*c^2), b = 108/c^2+5013*A[1]/(8*c^2), d = 27-693/(2*c^2)+117*A[1]-7113*A[1]/(4*c^2), e = -27+585/(2*c^2)-111*A[1]+20439*A[1]/(16*c^2), f = 1-3*A[1]-18/c^2-8*A[1]/c^2];
> S2 := eval(S[1], PARAM);
> series(%, c = infinity, 3, A[1] = 0, 2);
> simplify(%)

I was given that solitary initial state to see how it will deform as time goes on. am struggling to get my code so that I can get video frames. please help on how I can generate my code

u_o(x)= a₀x²(1-x)² for x (less than or equal to) x (less than or equal) 1

u₀(x)    = 0 for x > 1

the video clips will be representing the function u(*,t) :x to u(x,t)

for a sequence of choices of t such as t=0; t=0,5...t=3

 “Error, too many levels of recursion” ,but there’s just a single expression.

How can this happen?

I am using Maple 15 to numerically solve a system of differential algebraic euqations (DAE) with given initial conditions, and I've tried rfk45_dae and rosenbrock_dae solver, but both solver responded in error like this

Error, (in dsolve/numeric) cannot numerically solve complex DAE initial value problems, the system must be converted to a real system

I don't understand what is a real system, and how could i convert it to a real system.

I'm running a long loop with a lot of variables. I have noticed that Maple does not seem to clear its memory after each loop iteration, which results in very large memory used after all the iterations. I can't use restart because I need a few variables to be remembered throughout the loop for analysis afterwards. So the question is how to clear the memory for selective variables and procedures at the end of each iteration.

I need to plot a function:



f(1.0) gives a correct result but plot doesn't. Could you help me with it?

Dear those who are in Mapleprimes,

As I can't understand how Maple calculate the quick sort, I write the present question, hoping that someone give me a hint.

In essence, nested procedure I cannot understand is this:

quicksort:=proc(A,m,n)

....................

if m<n then

quicksort(A,m,p-1);.................................(1)

quicksort(A,p+1,n)...................................(2) 

end if;

eval(A);

end proc:

Details were ommitted, but I have to say that p is the number between m and n, which is determined by ommitted parts of 

the procedure.

And, with this nested procedure, 

quicksort([2,4,1,5,3],1,5) is calculated.

What I want to know is how to process the parts of (1) and (2).

If after (1) is processed, (2) is processed, what is the value of p in (2).

Is it the p which is determined successively through processing nested value of (1)?

Thank you in advance.

taro

Can anyone help to compute the following integral in terms of the bessel functions in maple.

Hey guys! Can someone please help me by telling what I can insert into maple to get answer for this question? Thanks!

The help documents read，

“

 The function unames returns an expression sequence consisting of all the active names in the current Maple session which are ``unassigned names''.

“

But what unames() returns is obviously not the contents one expects:

i am trying to execute the following code but i am having the following error:

A:=Matrix(21,4):A(1,2):=0:A(2,2):=0:t:=2: thetasec:=-8.724679300*10^(20):  for z from 0.1 by 0.05 to 1 do  t:=t+1: A[t,1]:=z:  x:=2*A[t-1,2]-A[t-2,2]+thetasec*0.05^(2):  theta2:=evalf(arctan(sin(x-Pi),cos(x-Pi))+Pi):    if theta2>Pi/(2)and theta2<=(3*Pi)/(2)then   A[t,2]:=theta2-Pi   elif theta2>(3*Pi)/(2)then A[t,2]:=theta2-2*Pi else  A[t,2]:=theta2 fi:  A[t,3]:=cos(A[t,2]):  A[t,4]:=sin(A[t,2]):od

Error, cannot determine if this expression is true or false: (1/2)*Pi < 3.535344555 and 3.535344555 <= (3/2)*Pi

what is causing this error and how can i fix it 

I'm using Maple 12 to solve a system of differential equations numerically. I first define my system as "sys1" and then use the command:

sol1 := dsolve(sys1, numeric, output = listprocedure, range = 0 .. 2000)

I'm using output=listprocedure because that's what the Maple's Help says if I want to use individual solutions. So my differential equation system has 8 solutions, and I label them a1(t) through a8(t). Now after solving the system I want to be able to evaluate, e.g., a1(t) at t=100.

I then follow the Maple's Help by defining:

f1(t):=eval(a1(t),sol1)

But then if I do:

f1(100)

I don't get the expected numerical value. Instead I get a1(100) as the result.

What I managed to do however was to plot f1(t) with the following command:

plot(f1(t),0..2000)

So it seems that I did it partially right. However according to the Maple's Help I should be able to extract numerical values with f1(100). 

I'd appreciate any suggestions!